If prcnt incr. from A to B is 20% and prcnt decr. from B to A is 16.67%, what is A?

C

CST

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Hi all,

How do I solve this maths problem?

If the percent increase from A to B is 20% and the percent decrease from B to A is 16.67%, what is the value of A?

I start off by formulating these 2 equations below

(B-A)/A = 20% --------------- (1)
(B-A)/B = 16.67% ------------ (2)

But isn't this contradicting each other? The other method is by substituting a figure example like A = 100, but isn't this guessing work?

Thanks all for helping :)
 
CST said:
Hi all,

How do I solve this maths problem?

If the percent increase from A to B is 20% and the percent decrease from B to A is 16.67%, what is the value of A?

I start off by formulating these 2 equations below

(B-A)/A = 20% --------------- (1)
(B-A)/B = 16.67% ------------ (2)

But isn't this contradicting each other? \(\displaystyle \ \ \ \ \ \ \)No, they complement each other. **

The other method is by substituting a figure example like A = 100, but isn't this guessing work?

Thanks all for helping :)
Click to expand...

** They are equivalent equations. (16.67% is the rounded value for 1/6.)

A can be any positive value based on what is given.

There is not enough information given to determine a unique A.
 
CST said:
(B-A)/A = 20% --------------- (1)
(B-A)/B = 16.67% ------------ (2)

But isn't this contradicting each other?
Click to expand...

Can you explain why you were thinking about a contradiction?

These equations are correct; they model the given information.


The other method is by substituting a figure example like A = 100, but isn't this guessing work?
Click to expand...

Sure, but guessing and checking is often a solution method (unless you were told not to do that).

Lookagain is correct; there are infinite solutions for A.

However, you can state A in terms of B (that is, find a formula for A, given some value for B).

Solve the system for A. :cool:
 
Otis said:
Can you explain why you were thinking about a contradiction?

These equations are correct; they model the given information.

Sure, but guessing and checking is often a solution method (unless you were told not to do that).

Lookagain is correct; there are infinite solutions for A.

However, you can state A in terms of B (that is, find a formula for A, given some value for B).

Solve the system for A. :cool:
Click to expand...

Hi Otis,

Contradiction is the wrong word; should be complement as mentioned by Lookagain.

Thanks heaps.
 
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